Quarter-Micrometer Gate Ion-Implanted GaAs MESFET’s with an ftof 126 GHz

We report fabrication and characterization of a 0.25-µm gate ion-implanted GaAs MESFET with a maximum current-gain cutoff frequency ft of 126 GHz. Extrapolation of current gains from biasdependent 5-parameters at 70-100 percent of Idssyields ft’s of 108-126 GHz. It is projected that an ft of 320 GHz is achievable with 0.1-µm gate GaAs MESFET’s. This clear demonstration of ft’s over 100 GHz with practical 0.25-µm gate length substantially advances the high-frequency operation limits of short-gate GaAs MESFET’s.